Abstract

The discovery of graphene has inspired extensive interest in two‐dimensional (2D) materials, and has led to synthesis/growth
of additional 2D materials, generally referred to as ‘Beyond Graphene’. Notable among the recently discovered exotic 2D materials
are group IV elemental monolayers silicene and germanene, group V elemental monolayer phosphorene, and binary monolayers,
such as hexagonal boron nitride (h‐BN), and molybdenum disulfide (MoS2
). Environmental effect on the physical and chemical properties of these 2D materials is a fundamental issue for their practical
applications in devices operating under ambient conditions, especially, exposure to air often leads to oxidation of nanomaterials
with significant impact on the functional properties and performances of devices built with them. In view of its importance,
we present here a review of the recent experimental and theoretical studies on the oxidation of 2D materials focusing on the
relationship between the oxidation process and the energy values which can be calculated by first principles methods. The
complement of experiments and theory facilitates the understanding of the underlying oxidation process in terms of cohesive
energy, energy barrier to oxidation and dissociation energy of oxygen molecule for 2D materials including graphene, silicene,
germanene, phosphorene, h‐BN, and MoS2. WIREs Comput Mol Sci 2017, 7:e1280. doi: 10.1002/wcms.1280

Degradation of phosphorene. (a) AFM image of phosphorene after exfoliation, (b) after a few days under ambient conditions, (c) Raman spectra measured in air at 24, 48, 96, and 120 min after exfoliation, (d) time dependence of the integrated intensity of the Ag2 mode in different conditions, (e) time evolution of the integrated Ag2 mode at different laser fluences. (Reprinted with permission from Ref . Copyright 2015 Nature Publishing Group)

Oxidation of silicene on Ag (111). (a) XPS line of silicene epitaxially grown on Ag (111), (b) STM topography of silicene with different domains, XPS of silicene exposed to 1000 L of O2 (c), to air for 3 min (d), and to air for 1 day (e). (Reprinted with permission from Ref . Copyright 2013 Wiley‐VCH Verlag GmbH & Co.)

Oxidation resistance of graphene coated Cu or Ni. (a) illustration of graphene as a chemically inert diffusion barrier, (b) photograph of graphene coated and uncoated penny after H2O2 treatment for 2 min, (c) photograph of Cu and Cu/Ni foil with and without graphene coating taken before and after annealing in air at 200°C for 4 h. (Reprinted with permission from Ref . Copyright 2011 American Chemical Society)